[CP2K-user] Cell optimization using ASE

[Lucas Bandeira]

Dear cp2k group,

I am trying to perform some cell optimization using cp2k interfaced with
ASE. The command lines I am using are the following:

sys=bulk('Cu', 'fcc', a=3.7, cubic=True)
sys.calc = calc
opt=BFGS(sys, trajectory='CuBulk.traj', logfile='CuBulk.log',
restart='Cubulk.rst')
opt.run(fmax=0.01)

This is based on this ASE tutorial:
https://wiki.fysik.dtu.dk/ase/gettingstarted/surface.html.

However, as I have seen, the maximum force on each atom oscillates about
the same range 0.6-0.8 eV/A (for a Cu unit cell), and it also depends on
the metal I am working with. To be honest, I chose this value for fmax
because I thought it was the convergence criteria for the maximum force
between two consecutive optimization steps. My question is: How do I choose
the maximum value for the force on each atom, or any other convergence
criteria? Is this the right way to perform cell optimization using ASE?

Yours faithfully,

Lucas Bandeira
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